Zynga has added its most popular title - CityVille - to games that can be played at the Google+ social network recently launched in a challenge to Facebook.
"It's no secret we're big fans of Google+ here at Zynga," the San Francisco-based startup said in a blog post.
"Last month we announced that we partnered with Google to bring Zynga Poker to Google+, and today we're excited to add CityVille+ to the new game platform," the message continued.
In August, Google+ opened a gaming zone at the fast-growing social network vying with Facebook to be the hub for people's online lives.
Along with global game sensation Angry Birds, the initial array of offerings available at Google+ included Bejeweled Blitz, Zynga Poker, and Dragon Age Legends.
Google is reported to be among the investors in Zynga, which has filed paperwork with US securities regulators for an initial public offering aiming to raise about US$1 billion from the markets.
Zynga in July made its debut in Mainland China with a localised Zynga City title launched in an alliance with leading Chinese internet service Tencent.
The free online game is a Chinese version of CityVille, which was playable in French, German, Italian, Spanish, and English when it was released in December.
In the game, players build dream cities complete with businesses, homes, park and landmarks and then invite friends to take up virtual residence in the form of animated characters that run shops, enforce laws, and more.
CityVille has slightly more than 72 million monthly active users, according to figures available online from market tracker AppData.
Four-year-old Zynga rose to stardom with the popularity of its free-to-play games at social networking titan Facebook.
"Ultimately, we want to make our games accessible to everyone, everywhere - no matter where they play or what platform they play on," Zynga said.